This close-up view of the F-1 engine for the Saturn V S-IC (first) stage shows the engine's complexity, and also its large size as it dwarfs the technician. Developed by Rocketdyne, under the direction of the Marshall Space Flight Center, the F-1 engine was utilized in a cluster of five engines to propel the Saturn V's first stage, the S-IC. Liquid oxygen and kerosene were used as its propellant. Initially rated at 1,500,000 pounds of thrust, the engine was later uprated to 1,522,000 pounds of thrust after the third Saturn V launch (Apollo 8, the first marned Saturn V mission) in December 1968. The cluster of five F-1 engines burned over 15 tons of propellant per second, during its two and one-half minutes of operation, to take the vehicle to a height of about 36 miles and to a speed of about 6,000 miles per hour.